What Are Haplogroups?


What’s up everyone I’m Halleta Alemu and welcome to another episode of The DNA Download where we explain the
science of genetics so you can live in the know! When people talk about their
DNA results I keep hearing the word haplogroups. Joining me today is Dr.
Samantha Esselman, a scientist from the 23andMe Ancestry team who can unpack
this concept. So Samantha what are haplogroups? Truly it sounds like a word my dad would make up in Scrabble. Well it’s definitely a real word. A haplogroup
is a grouping or an assignment of similar sets of patterns in people’s
DNA so it’s kind of like if we were to group people based on something like
their zip codes and then we can use these patterns of DNA to trace the
ancient origins of your ancestry. Okay so, then how do you make these groupings
from DNA? So people have two special pieces of DNA which we use to define two different kinds of haplogroups. The first kind is paternal haplogroups
traced through Y chromosomes which get passed exclusively from fathers to sons.
And the second kind is maternal haplogroups traced through mitochondrial
DNA, which gets passed from mothers to both sons and daughters. Okay, then what
makes these two pieces of DNA special? So that’s a great question. It’s because the
inheritance pattern is really simple especially compared to the rest of your
genome and actually the beginning of the word haplogroup, “haplo” comes from the
Greek word “aplos” which means simple. Oh, well that’s a good
memory jogger. Yeah and so most of our DNA comes from a sort of random
shuffling of our parents DNA which can make it difficult to figure out which
side of the family each piece comes from But then Y chromosomes and mitochondrial
DNA don’t get shuffled But then if they aren’t shuffled, why aren’t everyone’s haplogroups exactly the same? That’s a great question. So over the more than
200,000 or so years of human evolution the occasional DNA changes occurred and
got passed on creating new haplogroups. Okay…? I have an analogy. So
imagine a guy thousands of years ago and this guy has a special recipe for his
you know award-winning Paleo soup. Oh, okay! And then he along with his brothers
inherited this recipe from his dad who got it from his dad and all the men in
the family faithfully stick to this recipe, no changes. Well I could go for some paleo soup right about now, but please go on. Yeah, this analogy always
makes me hungry. Okay good! And so then many generations later you know a great-great-great grandson adds some cilantro and then this great-great grandson
passes on a slightly modified version of this recipe to his sons and all the men
on his branch of the family trees start following this new cilantro recipe. And
so now if you think about it there are essentially two soup haplogroups and
this is pretty much how haplogroup inheritance works. That makes a lot of sense and since I’m a woman and I don’t have a Y chromosome, how can I trace my
paternal haplogroup? Yeah, so what you can do is you can learn from relatives who share your paternal line and so this would be something like a dad or a
brother. Okay cool! So then what about the mother’s side the maternal haplogroups? Right! You can trace this other kind of haplogroup through the DNA found in our cell’s mitochondria which turn the food we eat into usable energy for our cells. Ah, the powerhouse of the cell. You know your biology memes. Yeah so this mitochondrial DNA gets passed from moms
to both sons and daughters. Well thanks mom! So how can we use haplogroups
to trace our ancestry? So closely related haplogroups tend to share geographic
roots and so scientists can use the kind of modern distributions of haplogroups
around the world to trace some of these major migrations and then these can help
you understand where you fit into this ancient family tree of all humans. Wow! I feel like the world has got a whole lot smaller. Thanks for being here
Samantha and see you next time on The DNA Download

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